1. Field
The present disclosure generally relates to acoustic structures, and deals more particularly with a method and apparatus for installing acoustic devices in cellular cores.
2. Background
Acoustic structures are used in a wide variety of applications to attenuate noise. For example, one type of an acoustic structure used to reduce noise in aircraft engines aircraft engines is an acoustic liner comprising a panel construction in which a cellular core is sandwiched between a perforated inner skin and a non-perforated outer skin. The cellular core may have a septum in each of the cells in order to increase the acoustic performance of the liner.
There are at least three known methods for septumization of honeycomb cores, each of which is time consuming and labor intensive, in part because each septum must be individually placed in a cell of the core. The first method requires splitting the core and using an adhesive to bond a septum layer between the split cores. The second method involves a lost wax process which creates a buried septum, where a honeycomb core is pressed into wax. A thin layer of liquid resin floats on top of the wax which is then cured to form a solid layer and the wax is melted out of the honeycomb core. The third method involves using an automated robotic process where individual septum pieces with tabs are inserted one-by-one into each honeycomb cell. The tabs of the individual septum pieces are bonded to the honeycomb cell walls by carefully dipping the honeycomb panel to a certain depth into a liquid adhesive.
Accordingly, there is a need for a method and apparatus for placing acoustic devices such as septums in a cellular core that is both rapid and cost-effective. There is also a need for a method of producing acoustic structures that is more highly automated and efficient than has been heretofore possible.